As far as I am aware, Windows 11 requires UEFI boot. The VM is configured for UEFI. That's actually the default these days.
Regarding UltraISO, it looks like it makes it easy to just delete a file from an ISO and save the ISO back, but the trial has a limit of 300MB, so I can't verify that it actually works. I am on the fence for the $20. I might never use it again except for this one time.